The last time electric trolley cars hit the height of popularity was back in the Gay Nineties – not the 1990s, the 1890s – when webs of wire ruled the skies above city streets. Now the global company Siemens proposes a high-tech version of the good old days of electrified travel in the form of a new “eHighway of the Future” concept.
Before you get all excited about turning your new Focus EV into a personal mini-trolley, though, Siemens designed the concept for trucks in the long distance freight market. Passenger cars will have to wait their turn.
The growing problem of diesel emissions
Siemens forecasts a demand for eHighway both as a cost-saving measure for trucking companies and as a means of managing emissions from an expected increase in truck traffic.
According to Siemens CEO for U.S. Infrastructure and Cities, Daryl Dulaney, freight transportation on U.S. highways is expected to double by 2050.
Also contributing to the problem is an increase in overseas shipping, which makes diesel emissions concentrated in coastal cities as trucks from a widespread network of inland highways funnel into port regions.
An eHighway test for U.S. ports
In that context, it’s not surprising that Siemens is kicking off eHighway in the U.S. with a pair of planned demonstration projects at the ports of Los Angeles and Long Beach as a connection to cargo centers. Another pilot project is already underway in Germany and has proved a success so far.
Siemens’s eHighway concept shares the fundamental principle of trolley infrastructure, which is that trolley cars share roadways with other traffic rather than traveling along a dedicated road bed.
Trolleys are powered by electricity from an overhead wire called a catenary. Though the trolley car cannot stray out of the lane that sports a catenary, cars and trucks can move seamlessly across all lanes. That leaves an opening for diesel-electric trucks to travel along a conventional road on diesel fuel, and then hitch up to a catenary wherever one is available.
Core elements of the eHighway
Siemens already has electric hybrid technology under its belt through its ELFA hybrid drive system, which is designed to enable vehicles to switch between an internal combustion engine and electrical power from other sources including batteries and fuel cells.
In addition to the advanced diesel-electric hybrid system, two other new technologies go into the eHighway system. One is a two-way electrical transmission system, which is a step up from the one-way power supply used in conventional trolley lines.
The two-way system supplies energy to a diesel-electric truck through the catenary, just like a conventional trolley system. The new twist is that it also reclaims energy from the truck through regenerative braking. Regenerative braking is a system for capturing energy from friction that would otherwise go to waste as heat. Regenerative brakes are becoming commonplace for vehicles, elevators, shipping cranes, and other mechanical devices that stop frequently.
The other component of eHighway is a “smart” pantograph. A pantograph is a contraption that sits on the roof of a trolley car and transmits energy from the overhead wires to the electric motor. For eHighway, diesel-electric trucks would be equipped with a rooftop pantograph that could, among other things, sense when overhead electricity is available.
When the driver enters an electrified lane, the pantograph would raise to meet the catenary. The driver would not have to leave the cab to accomplish the connection, which can be made automatically or by pushing a button.
The pantograph has some degree of flexibility, so the driver can maneuver as needed within the lane while still maintaining contact with the catenary. Upon leaving the electrified lane, the pantograph retracts and the truck switches back to diesel mode just as seamlessly.
According to Siemens, the transition can be accomplished at speeds of up to 90 kilometers/hour, based on the results of its pilot project in Germany. The system also performs equally well in all weather conditions.
Benefits of the eHighway
The environmental advantages of eHighway are obvious in local areas, where it would virtually eliminate diesel emissions including carbon dioxide, nitrogen oxides and soot. It would also make a significant dent in traffic noise.
Aside from that, Siemens notes the bottom line benefit of saving money on diesel fuel. Since electric motors are typically more durable than diesel engines, the system could also save on maintenance, repair and replacement costs.
The sticky wicket would be the cost of installing the system, but according to Siemens that is not as daunting as it could be.
The substation that provides power to the catenary system is designed to fit into a shipping container, which can be installed without requiring a major construction project. In any case, the major feature of the eHighway infrastructure – namely, road – already exists without the need for modification.
Image: Courtesy of Siemens.
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